Carnitine and its use in the treatment of arrhythmia and impaired cardiac function

ABSTRACT

ARRHYTHMIA AND IMPAIRED CARDIAC FUNCTION ASSOCIATED WITH CONGESTIVE HEAT FAILURE AND SHOCK ARE OFTEN DRAMATICALLY REVERSED THROUGH ADMINISTRATION, EITHER ORALLY OR PARENTERALLY, OF B-HYDROXY-Y-TRIMETHYLAMINOBUTYRIC ACID OR THE SALT THEREOF.

United States Patent 3,830,931 CARNITINE AND ITS USE IN THE TREATMENT OF ARRHYTHMIA AND IMPAIRED CARDIAC FUNCTION Stephen L. De Felice, 430 Topping Hill Road, Westfield, NJ. 07090 No Drawing. Filed Nov. 6, 1972, Ser. No. 303,772 Int. Cl. A611; 27/00 U.S. Cl. 424-319 4 Claims ABSTRACT OF THE DISCLOSURE Arrhythmia and impaired cardiac function associated with congestive heart failure and shock are often dramatically reversed through administration, either orally or parenterally, of 13-hydroxy-y-trimethylaminobutyric acid or the salt thereof.

DETAILED DESCRIPTION The present invention pertains to the alleviation and treatment of certain aspects of congestive heart failure and shock, in particular the elimination of arrhythmia and the improvement of myocardial con-tractility. At pres cut, the drugs of choice in congestive heart failure are the cardiac glycosides such as digitalis. The administration of digitalis however is somewhat limited. While the drug is absorbed orally, beneficial cardiac effects are often not observed until two to six hours after administration. In those cases of life or death in which the drug must be rapidly administered, as well as in those conditions such as coma and vomiting in which oral administration is impossible, the drug can be given intravenously but this route is extremely dangerous and requires careful attention to dosage and previous digitalis medication.

It has now been discovered that improvements in myocardial contractility and systolic rhythm in congestive heart failure can often be obtained through administration of B-hydroxy- -trimethylanfinobutyric acid, or salt thereof. This substance is a well known compound, also known as carnitine, which has been safely used for a number of years for different indications. For example, the compound is sold in Europe as an appetite stimulant, and it has been reported that the material has an effect on the growth rate of children; see e.g. Borniche et al., Clinic Chemica Acta, 5, 171-176, 1960 and Alexander et al., Protides in the Biological Fluids, 6th Colloquium, Bruges, 1958, pp. 306-310. Investigation of the drug as an antagonist of thyroid hormone in cases of hyperthyroidism has also been reported, Gilgore et al., Uournal of New Drugs, 6, No. 6, 319-320 (1966) and =DeFelice et al., [00. cit., 6, No. 6, 351353 (1966). Finally, the use of the drug in the treatment of angina pectoris has been described in my copending application, Se-r. No. 157,741 filed June 28,1971.

While the mechanism of action of ,B-hydroxy- -trimethylaminobutyric acid in these various conditions is not fully understood, there is no immediately apparent reason to expect from these previous uses the dramatic effect which B-hydroxy-q -trimethylaminobutyric acid demonstrates in the treatment of congestive heart failure.

,6-Hydroxy-' -trimethylaminobutyric acid demonstrates a positive inotropic action on the myocardium, which contractile force is not associated with a decrease in heart rate. In addition to restoring the sinus rhythm to normal, fl-hydroxy- -trimethylaminobutyric acid results in a significant increase in cardiac output. Dramatic diuresis with reversal of the hypertension and urine reten tion which can accompany congestive heart failure is often seen, together with a restoration of pulse and blood pressure. Significantly, the toxicity of fi-hyclroxy- -trimethyl- 3,830,931 Patented Aug. 20, 1974 aminobutyric acid is remarkably low and the drug can thus be given orally or, more significantly parenterally, such as intravenously, without concern to toxic reactions.

The properties of ,B-hydroxy-y-trimethylaminobutyric acid in the treatment of congestive 'heart failure and arrhythmias in general can be seen in both animal models and clinical studies.

Thus in the isolated perfused Langendorf heart preparation, p3-hydroXy-'y-trimethylaminobutyric acid effectively minimizes the reduction in the force of myocardial contraction during periods of reduced blood flow. This protection lasts for at least 60 minutes with no adverse effect on the vital functions of the hear-t itself. This may be seen from the following.

Twenty adult mongrel dogs weighing from 10-12 kg. and of either sex were anesthetized with sodium pentobarbital, 30 mg./ kg. A polyethylene catheter was placed in the right femoral artery to allow for the rapid removal of blood. Clotting was prevented by injecting units/ kg. heparin (sodium) into the femoral vein. The chest was opened by a midline incision and all major branches of the ascending aorta, except the brachiocephalic trunk, were ligated. The reservoir chamber of the per-fusion system was filled with autologous blood drawn from the catheterized femoral artery of the same dog. The brachiocephalic artery was then cannulated with a short stainless steel cannula which was connected by polyethylene tubing to the pump perfusion circuit. At this time the descending aorta was ligated and the heat quickly removed from the chest cavity. The heart was then suspended in the heated reservoir chamber and perfused with 'blood by means of a Harvard peristalsic pump. The blood was maintained at 35 C. throughout and was oxygenated by bubbling 95% oxygen and 5% carbon dioxide into the reservoir chamber. Flow rates were found to vary slightly from heart preparation to heart preparation and ranged from to 250 ml./ min. Perfusion pressure was maintained at 25 to 50 mm. Hg and was used as a direct index of coronary vascular resistance.

Flow=c-onstant. A needle-tipped catheter connected to a Sanborn strain gauge and recorder was used to continuously monitor the perfusion pressure. Needle-tipped electrodes were placed into the ventricles of the heart to monitor electrocardiogram and heart rate. Force of contraction was measured via a Walton-Brodie strain gauge arch sutured to the left ventricle.

Following a 30-minute equilibration period the blood flow to the heat was reduced by 50%. Five minutes after the reduction of coronary flow the change in force of contraction was measured. This reduction in force is expressed as percent change from control. In most preparations this procedure was repeated twice prior to the administration of ,B-hydroxy-y-trimethylaminobutyric acid. The dose of fi-hydroxy 'y trimethylaminobutyric acid varied from 50 to 250 mg, and was injected directly into the inflow side of the perfusion circuit leading directly into the inflow side of the perfusion circuit leading directly into the heart. At from 5 to 60 minutes after injection of fl-hydroxy 'y trimethylaminobutyric acid, the coronary blood flow was again reduced by 50% and the change in force measured. Only those hearts in which repeated measurement could be obtained were included in the study.

In each of the 20 isolated perfused hearts, a reduction in coronary flow produced a significant decrease in force of contraction. Percent decrease prior to administration of 18-hydroxy-y-trimethylaminobutyric acid varied from 55% to 85% with a mean of 71:5. One hundred mg.

of fi-hydroxy 'y trimethylaminobutyric acid limited the percent decrease in force of contract-ion to from 196:3.4 to 28.4:79. At a dose of 150 mg, the percent decrease in force was from 25.0-11.2 to 295:9.7. Following the administration of 200 mg., the decrease in force of contraction following a 50% reduction in blood flow was from 25.0:64 to 27314.1. There is a significant differerence between the control decreases in force of contraction and those noted following administration of ,8- hydroxy-y-trimethylaminobutyric acid. In no instance was there an overlap between control and treated measurements of reduced flow standard deviation.

fl-hydroxyy-trimethylaminobutyric acid also demonstrates a significant elfect on failing heart-lung preparation, as can be seen from the following:

A series of adult mongrel dogs were anesthetized with pentobar-bitol sodium, mg./kg., and the chest of each opened via a midline incision. The ascending aorta was cannulated by inserting a large bore polyethylene catheter into the brachiocephalic artery and advancing it into the aortic circulation. The descending aorta and the subclavian artery were then ligated following injection of heparin sodium, 1000 units/kg. The aortic catheter was connected to a heated blood bath into which all cardiac output was pumped. The bath was also connected to a second large catheter which was inserted into the superior vena cava. The azygos vein and the inferior cava were ligated. A bilateral vagotomy was performed. Aortic blood flow, heart rate, venous pressure, reservoir level and left ventricular force of contraction were continuously monitored. Resistance to aortic fiow was then increased by 200% for 30 minutes, causing a progressive decrease in flow, heart rate and force of contraction. At 30 minutes, resistance to flow was decreased from 200% to 100% of control values. No significant recovery of force, rate or flow was noted in untreated heart-lung preparations. Those preparations given 250 mg./kg. of B-hydroxy-ytrimethylaminobutyric acid just prior to decreasing the resistance to flow at 30 minutes demonstrated a 50 to 75% recovery of force of contraction, heart rate and flow rates. These changes persisted for 30 to 60 minutes or until termination of the experiment (usually at 1 to 1 /2 hours).

The effect of fi-hydroxy-v-trimethylaminobutyric acid on atrial flutter and ventricular arrhythmias associated with congestive heart failure, and a comparison with the corresponding effect of ouabain, can be seen from the following:

Twenty adult mongrel dogs, anesthetized with sodium pentobarbital, 30 mg./kg., were placed in severe heart failure using a method described by Gattschalk. Electrical stimuli were applied to the atrial appendages of the heart to induce atrial flutter and ventricular arrhythmias. Following 30 minutes of decreased cardiac work and ventricular arrhythmias, the dogs were given either ouabain (1 mg./kg.) or fl-hydroxy-y-trimethylaminobutyric acid (20 mg./kg.). Ouabain produced a 40%i10% increase in the force of contraction, a 20% i-5% decrease in the heart rate, and a 32% 5% increase in the cardiac output. Overall cardiac work increased 20% i2%. No antiarrhythmiac effects were observed. The dogs treated with fl-hydroxy-y-trimethylaminobutyric acid showed an 85% increase in force of contraction, a i-l0% increase in heart rate, and a 90% :12% increase in cardiac output. Cardiac work increased 60% and 15%, and in 8 of 10 dogs, the arrhythmias were converted to a normal sinus rhythm.

The antiarrhythmic effect noted above can be more clearly seen in daunomycin-induced arrhythmias in both the Langendorff preparation and in intact Rhesus monkeys.

In a series of 20 isolated perfused Landendorff preparations, daunomycin was administered in a dose of 100 mg./kg. thereby consistently producing ventricular arrhythmias, tachycardia, and severe arrhythmias. Following 30 minutes of the severe arrhythmias, ,B-hydroxy-ytrimethylaminobutyric acid was administered in doses of from 50 mg. to 500 mg. In 18 of the 20 isolated heart preparations, the arrhythmias noted were eliminated. The arrhytmias which were eliminated did not reappear for periods up to 60 to minutes.

Twelve intact monkeys were likewise given daunomycln at a dose of mg./kg. After 15 to 30 minutes of observed arrhythmias, ,B-hydroxy-y-trimethylaminobutyric acid was administered intravenously in a dose of 100 to 250 mg. In 9 of the 12 intact monkey preparations, the arrhythmias were eliminated. The monkeys were followed for from 8 to 12 hours using continuous recording techniques. No further arrhythmias were noted. No toxic manifestation was noted and all of the monkeys upon subsequent autopsy gave negative pathological reports.

The observations noted above in various laboratory models were confirmed in clinical studies which are briefly summarized below.

Case 1 A patient with carcinoma of the colon had both ureters implanted into his colon. Before surgery he was hypertensive and had a left branch block. After surgery, his blood pressure fell to 90/ 40. B-hydroxy-'y-trimethylaminobutyric acid was given as a single IV dose of 500 mg. and within 60 seconds the blood pressure was 160/90. The cardiac rate fell from to 85. The patient put out 615 cc. of urine within an hour after fi-hydroxy-v-trimethylaminobutyric acid was given, 400 cc. of which were excreted within the first 30 minutes. In the previous nine hours there was a total urine output of less than 400 cc. His QRS complex on the EKG averaged 0.11 before administration and two minutes after administration averaged around 0.089. A few days later his blood pressure dropped from the previous consistent level of approximately 160/ 80 to /70. He was then given another dose of 500 mg. IV and within 60 seconds his blood pressure rose to 180/80.

Case 2 A similar type of operation, i.e. carcinoma of the colon and bilateral implantation of ureters, had been performed. The patient suddenly became hypotensive and entered the intensive care unit. He had a cardiac rate of 125 and the blood pressure was not detectable. A single IV dose of 500 mg. of ,B-hydroxy-v-trimethylaminobutyric acid was given. In 15 minutes, the systolic pressure was 80. Total urinary output for the twenty-four hours preceding this dose of hydroxy-y-trimethylaminobutyric acid had 175 cc. The urinary output for 24 hours following fl-hydroxy-y-trimethylaminobutyric acid administration was 970 cc., a substantial portion of which occurred within an hour. The patient had atrial fibrillation before the administration of the drug. which disappeared within 30 seconds. The normal sinus rhythm which occurred was maintained.

Case 3 The patient, age 50, had a myocardial infarct with a history of hypertension. He went into cardiogenic shock and his blood pressure was not measurable. He responded to norepinephrine and his blood pressure rose to 85/ 65. He developed a gallop rhythm. He was given 500 mg. of B-hydroxy-y-trimethylaminobutyric acid in two doses thirty minutes apart. His blood pressure rose to 100/ 70 and his urinary output rose to cc./hour (compared with a previous output of 10 cc./ hour). The gallop rhythm remained.

Case 4 A 63 year old male was hospitalized repeatedly for cardiac failure due to congestive heart failure. He had been treated for 14 years with cardiac glycosides and had intermittent cardiac irregularities. Upon this admission, the patient was found to be in cardiac failure with severe and continuing arrhythmias and no detectable blood pressure despite a continuous infusion of levophed. The patient was then given 500 mg. of ,B-hydroxy- -trimethylaminobutyric acid. An immediate recovery of normal sinus rhythm, an improved cardiac output and a detectable blood pressure within the normal range were noted. Within one hour after administration, the patient, who had previously been anuric for 6 hours, began to put out significant quantities of urine. This improved condition persisted for 24 hours. The patient received no further treatment with the drug.

Case 5 A 42 year old male with a history of cardiovascular difficulties ranging from early hypertension to mitral valve replacement was admitted with congestive heart failure. The patient had previously been treated with coronary vasodilators and/or cardiac glycosides. Following 28 hours of supportive therapy, to which he was non-responsive, the patient was given 500 mg. of fl-hydroxy-ytrimethylaminobutyric acid every four hours. The clinical response of the patient Was evident within a few hours and he was essentially asymptomatic. After seven days he was discharged from the hospital. B-hydroxy-y-trimethylaminobutyric acid reversed both the cardiac arrhythmias and the congestive heart failure in this patient.

Case 6 A 62 year old male suffered a myocardial infarct but demonstrated no acute cardiovascular difficulties. [it-hydroxy-y-trimethylaminobutyrie acid was, nevertheless, given, in a dose of 500 mg., to determine whether there would be any cardiovascular effect. As expected, no detectable cardiovascular effect was observed over a period of two hours.

Case 7 A 58 year old male was admitted with an acute myocardial infarct. He had no great difliculty with his blood pressure but had premature ventricular contractions as noted on the EKG. An intravenous dose of 500 mg. of p-hydroxy-y-trimethylaminobutyric acid was given and within a few minutes his PVCs were greatly diminished. A second dose wa given ten minutes after the first dose and within a few minutes the PVCs completely disappeared. There was no noticeable effect on blood pressure.

Case 8 A 73 year old male patient with a large myocardial infarct entered the hospital in cardiogenic shock. Doses of 500 mg. of B-hydroxy-y-trimethylaminobutyric acid were given at -minute intervals. No detectable cardiovascular effect was observed.

Case 9 A 65 year old male was admitted to the hospital with severe congestive heart failure with marked pulmonary and peripheral edema. He was givenSOO mg. of fl-hydroxy-y-trimethylaminobutyric acid every 15 minutes for over a period of approximately one hour, for a total of four doses. A diuresis immediately followed and within a period of four hours his clinical condition was markedly improved and his dyspnea virtually disappeared.

Case 10 A 78 year old female was scheduled for a cholecystectomy. Her pulse was 55 (left bundle branch block) and the anesthesiologist would not handle the patient until her pulse was higher. Atropine was given without a response. An automatic cardiac pacemaker was inserted and the patients pulse rate went to 80. After surgery the patient did well until the pacemaker was turned off. Her pulse immediately fell to 58-60. li-hydroxy-y-trimethylaminobutyric acid was administered and her pulse immediately went to 76. This same phenomena occurred twice with the next hour; i.e. pulse fell and the drug reversed the fall. After .the second administration, the patient was once again placed on the pacemaker. When the pacemaker was turned off the pulse immediately fell. The third dose of B-hydroxy-v-trimethylaminobutyric acid was then given and the pulse immediately rose. From that point on the pacemaker was not required to maintain a regular pulse that was 70 or over.

Case 11 A 63 year old female was operated upon to correct a small bowel fistula. She had cancer of the bladder and had undergone bladder irradiation. Postoperatively she had excessive vaginal bleeding that was emanating from the bladder. Her blood pressure began to fall and her pulse rate increased. Eventually, her blood pressure was undetectable and her pulse fell to 60. ,B-hydroxy-y-trimethylaminobutyric acid, 500 mg, was given and almost immediately her systolic pressure rose to and her pulse to -120. In approximately one hour, her blood pressure was again undetectable and her pulse rate was 50. Once more 500 mg. of ,6-hydroxy-v-trimethylaminobutyric acid administration her systolic blood pressure rose to 90 and her pulse to 100. Additional administration of the drug was not made.

Case 12 An 86 year old male was admitted with a diagnosis of severe anemia and congestive heart failure. He was found to have carcinoma of the colon. He was digitalized and given 5 pints of blood whereupon he was operated upon. Following surgery his EKG showed many ectopic beats and a bundle branch block. Extrasystoles became quite prominent. Blood pressure was 134/80 and pulse 58. He was given 500 mg. of fi-hydroxy-y-trimethylaminobutyric acid intravenously over a 5 minute period and before drug administration was completed, the cardiac arrhythmias were markedly reduced. He had previously failed to respond to atropine. Three subsequent doses were given over a period of an hour whereupon his arrhythmia disappeared except for an occasional ectopic beat. His PR interval shortened to a first degree heart block. A normal sinus rhythm continued throughout his hospital stay. Digitalis was stopped before surgery.

fl-hydroxy-y-trimethylaminobutyric acid contains a center of asymetry and thus exists in two stereoisomers. Either the racemate or the individual isomers can be employed. While the racemate can be conveniently employed, it appears the L-isomer is more active while the D-isomer is slightly more toxic. Thus the LD in the mouse is as follows:

In actual practice, fl-hydroxy-y-trimethylaminobutyric acid is administered parenterally or orally in any of the usual pharmaceutical forms. These include solid and liquid oral unit dosage forms such as tablets, capsules, powders, solutions, syrups and the like, including sustainedrelease preparations, and fluid injectable forms such as sterile solutions and suspensions. The term unit dosage form as used in this specification and the claims refer to physically discrete units to be administered in single or multiple dosage, each unit containing in association with the carrier, the predetermined quantity of fl-hydroxy-v-trimethylaminobutyric acid calculated to produce the desired effect upon administration of a specific number, one or more, of such units.

Powders are prepared by comminutin-g fi-hydroxy-y-trimethylaminobutyric acid to a suitable fine size and mixing it with a similarly comminuted diluent pharmaceutical carrier such as an edible carbohydrate material as for example, starch. sweetening, flavoring, preservative, dis persing and coloring agents can also be present.

Capsules are made by preparing a powder mixture as described above and filling formed gelatin sheaths. A lubricant such as talc, magnesium stearate and calcium stearate can be added to the powder mixture as an adjuvant before the filling operation; a glidant such as colloidal silica may be added to improve flow properties; a disintegrating or solubilizing agent may be added to improve the availability of the medicament when the capsule is ingested.

Tablets are made by preparing a powder mixture, granulating or slugging, adding a lubricant and disintegrant and pressing into tablets. A powder mixture is prepared by mixing fl-hydroxy-y-trimethylaminobutyric acid, suitably comminuted, with a carrier such as starch, sucrose, kaolin, dicalcium phosphate and the like. The powder mixture can be granulated by wetting with a binder such as syrup, starch paste, acacia mucilage or solutions of cellulosic or polymeric materials and forcing through a screen. As an alternative to granulating, the powder mixture can be run through a tablet machine and the resulting imperfectly formed slugs broken into granules. The granules can be lubricated to prevent sticking to the tablet forming dies by means of the addition of stearic acid, a stearate salt, talc or mineral oil. The lubricated mixture is then compressed into tablets. fi-hydroxy-y-trimethylaminobutyric acid can also be combined with free flowing inert carriers and compressed into tablets directly without going through the granulating or slugging steps. A protective coating consisting of a sealing coat of shellac, a coating of sugar or polymeric material and a polish coating of wax can be provided. Dyestuffs can be added to these coatings to distinguish different unit dosages.

Oral fluids such as syrups and elixirs are prepared in unit dosage form so that a given quantity, e.g., a teaspoonful, contains a predetermined amount of phydroxy-'ytrimethylaminobutyric acid. Syrups can be prepared by dissolving B-hydroXy-y-trimethylaminobutyric acid in a suitably flavored aqueous sucrose solution 'while elixirs are prepared through the use of a non-toxic alcoholic vehicle. Suspensions can be formulated by dispersing the compound in a non-toxic vehicle in which it is insoluble.

Fluid unit dosage forms for parenteral administration are prepared by suspending or dissolving a measured amount of B-hydroxy-y-trimethylaminobutyric acid in a non-toxic liquid vehicle suitable for injection, such as an aqueous or oleaginous medium, and sterilizing the suspension or solution. Alternatively a measured amount of fi-hydroxy-v-trimethylaminobutyric acid is placed in a vial and the vial and its contents are sterilized and sealed. An accompanying vial or vehicle can be provided for mixing prior to administration.

Of the above forms, the fluid unit dosage forms intended for injection, in particular intravenous and intramuscular injection, are preferred. Thus in contrast to the previously described uses of 3-hydroxy-y-trimethylaminobutyric acid where only oral administration was contemplated or even desirable, the treatment of cardial failure requires in certain instances a rapidly acting composition. Thus while solid and liquid dosage forms intended for oral administration have value in the treatment of certain arrhythmias and congestive heart failure, in particular maintenance therapy, the sterile liquid or fluid injectible unit dosage forms are the compositions of choice.

In addition to the free base, which can exist in Zwitterionic form, one can employ pharmaceutically acceptable salts such as the hydrochloride (m.p. 142). Since however fl-hydroxy-y-trimethylaminobutyric acid as the free base is itself soluble in aqueous media, utilization of a salt for solubility purposes is generally not necessary.

The dose which is administered must of course be determined from the age, Weight and condition of the patient, utilizing sound professional judgment. An effect can be observed at doses as low a 1 to 2 mg./kg. but generally the dose is from about 5 to about 10 mg./ kg. Larger doses can be given with relative safety in view of the low toxicity of the compound and such doses are often indicated when an insufficient response indicates an insufficient initial dose for the particular patient. Utilization of oral unit dosage forms also requires a somewhat larger dose than is employed. in the case of parenteral administration.

EXAMPLE A sterile aqueous suspension for intramuscular injection, containing in each ml. mg. of ,G-hydroxy-y-trimethylaminobutyric acid, is prepared from the following ingredients:

fi-hydroxy-v-trimethylaminobutyric acid gm 100 Sodium carboxymethylcellulose, low viscosity gm l0 Polysorbate 80, U.S.P. gm 4 Propylparaben, U.S.P. gm 0.4 Water for injection q.s. ml 1,000

What is claimed is:

1. The method of improving myocardial contractility and systolic rhythm in congestive heart failure and shock in a human in need thereof which comprises administering to said human an amount of fi-hydroxy-y-trimethylaminobutyric acid or a pharmaceutically acceptable nontoxic salt thereof suflicient to improve myocardial contractility and systolic rhythm.

2. The method of claim 1 wherein fl-hydroxy-y-trimethylaminobutyric acid or the hydrochloride salt is administered.

3. The method of claim 2 wherein the hydrochloride salt of fi-hydroxy-y-trimethylaminobutyric acid is administered in solution by injection.

4. The method of claim 3 wherein the amount of 5- hydroxy 'y trimethylaminobutyric acid administered is from about 5 to about 10 mg./kg.

References Cited UNITED STATES PATENTS 3/1942 Heyn 4243l6 9/1956 Borsook et a1. 424-316 US. Cl. X.R. 424-319 

